Bread containing wxsu2 genotype starch as an anti-stalent

ABSTRACT

Chemically and yeast leavened bakery products which have improved shelf lives are provided by the inclusion of an effective amount of a starch or flour selected from a plant of a wxsu 2  genotype in the bakery product dough. Breads which contain the starch or flour, preferably obtained from maize, are provided with a softer, moister crumb after baking as well as a fresher texture and appearance after a storage period.

BACKGROUND OF THE INVENTION

Due to the ability of consumers to critically discern small variationsin bread characteristics such as crumb texture, crust tenderness, grainstructure, loaf volume, and density, tremendous work has been done bythe baking industry to provide breads which are both physically as wellas organoleptically pleasing.

As used herein, the term "bread" is intended to apply generically tobakery products.

Staling is a principal concern in the industry due to the fact that itmay limit the shelf life of bread to only about three or four days inthe store plus a few additional days at home. Staling is defined asmeaning all of the changes which occur in bread during storage whichmake it less palatable, except those due to the action of spoilageorganisms. As bread stales, the crumb (interior of the loaf) becomesincreasingly tough and hard. Eventually the crumb becomes dry andcrumbly. These texture changes are accompanied by a decrease in thewater absorption capacity of the crumb. It is well believed that starchretrogradation or crystallization plays an important, though notexclusive, role in staling.

Various preservatives and humectants commonly employed in breads toimprove shelf life include such compounds as: lecithin,emulsifier/stabilizers such as mono- and diglycerides and certain estersthereof, stearyl tartrate, sodium or calcium stearoyl-2-lactylate, andsodium lactate. Much effort continues to develop natural means forretaining freshness and providing resistance to staling to bothchemically and yeast leavened bakery products.

An object of the present invention is to provide a bakery product whichhas improved shelf life and resistance to staling.

A further objective is to provide a process for naturally improving theshelf life and resistance to staling of a bakery product.

SUMMARY

This invention is directed to chemically and yeast leavened bakeryproducts with improved shelf-life provided by the addition of a starchor flour having the genetic composition wxsu₂, preferably derived frommaize, to the dough formulation. The aforementioned starch, when addedat about a 3 to 15%, preferably 5-10%, and most preferably 7-9%,substitution level based on the total farinaceous content of the doughresults in a bakery product with a softer, moister crumb after baking aswell as fresher texture and appearance after a storage period.

In addition to bread, other typical bakery products which would benefitfrom the addition of wxsu₂ starch include such items as fresh,refrigerated and frozen yeast-raised buns and rolls, yeast-raised sweetdoughs, and chemically leavened baked products such as muffins, quickbreads, cakes and biscuits.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a preferred embodiment the starch employed is extracted from maizegrown from double-recessive mutants of the waxy sugary-2 genotype,designated for purposes herein as wxsu₂. The waxy gene is located atposition 59 of Chromosome 9 of corn while the sugary-2 gene is locatedat position (57) of Chromosome 6. (See M. G. Nueffer, L. Jones, and M.Zuber, "The Mutants of Maize" (Crop Science Society of America, Madison,WI 1968), pp. 72 and 73.).

Also within the scope of this invention is the starch resulting fromwxsu₂ mutants wherein the wx and/or su₂ genotypes have been moved toanother portion of the plant genome by translocation, inversion, or anyother methods of chromosome engineering. In addition, starch extractedfrom a plant grown from artificial mutations and variations of the abovegenetic composition which may be produced by known standard methods ofmutation breeding is also applicable herein. Our designation of themutant as the wxsu₂ genotype is intended to mean that the mutant willnecessarily contain the wx and su2 genes, but is not limited thereto.

The waxy genotype imparts to the corn plant the ability to produce astarch which consists primarily or totally of amylopectin, and thephenotype, or physical expression, of the endosperm of the waxy genotypeis opaque with a hard waxy texture. The phenotype of the endosperm ofthe sugary-2 genotype, on the other hand, is translucent and sometimeswrinkled. The results of an investigation by R. Creech into the effectof sugary-2 and waxy gene mutations, singly and in combination, on themaize endosperm and the properties thereof are reported in Advances inAgronomy, Vol. 20 (Academic Press, 1968), pp. 275-322 and in Genetics,52, pp. 1175-1186, December, 1965. An article by R. M. Sandstedt, B. D.Hites, and H. Schroeder, entitled "The Effects Of Genetic Variations InMaize On The Properties Of The Starches", published as paper no. 1894,Nebraska Agricultural Experiment Station, describes several propertiesof starches obtained from various genetic mutants of maize includingwxsu2. The data in that report show the particular wxsu2 starch used tohave a greater sol stability to heat as well as a lower gelatinizationtemperature than the wx starch. Starches obtained from mutant maize arealso described by H. H. Kramer et al. in an article entitled "GeneInteractions In Maize Affecting Endosperm Properties" which appeared inAgron. J., 50, pp. 207-210 (1958).

To obtain the double-recessive mutant of the wxsu2 genotype in maize ina usual manner, one may, for example, cross a waxy mutant (wx) with asugary-2 mutant (su2), and thereafter self pollinate the firstgeneration single cross (Wx wx Su2 su2) to theoretically recover thedouble mutant in a 15:1 ratio from a segregating ear. The starchutilized in this invention may be obtained from inbred lines, but it ismore desirable that the starch be obtained from hybrids derived frominbreds containing the wxsu2 double-recessive mutant, ordinarily becauseof higher yields and other factors. While maize is the preferredspecific plant herein for the source of the waxy starch, the inventionis also applicable to other plant species such as, for example, waxyrice, waxy barley and waxy sorghum, provided that they are of wxsu2genotype.

Extraction of the starch and flour from the kernel of the maize grownfrom the double-recessive mutant seed may be carried out in a standardmanner by the wet-milling or dry-milling process well known in the art,but is not limited to such methods.

It is to be understood that the invention herein is meant to include notonly bakery compositions containing wxsu₂ starch or flour but also thosecompositions containing any ground products from the plant such as, forexample, grits, hominy, and meal.

While the use of natural unconverted and unmodified wxsu₂ starch ispreferred for the intended use herein, it is to be understood thatstarch which has been lightly converted or modified by typical processesknown in the art (i.e., etherification, esterification, andcrosslinking) may be employed in the bakery composition provided themodification does not deleteriously effect the bakery product.Dextrinized wxsu₂ starch however, is not recommended for use herein. Ithas been found that the dextrinized flour provides breads with a lowvolume and firmer texture as well as an undesirable off-taste.Pregelatinized wxsu₂ starch was also found to not provide any shelfstability benefits to bakery compositions.

The amount of substitution of wxsu₂ starch employed in the bakery doughcomposition is normally in the range of 3-15%, based on the totalfarinaceous content of the dough, and preferably 5-10%. In order todetermine the most effective amount of wxsu₂ starch necessary to providea bakery product with improved shelf stability many factors must betaken into consideration by the practitioner. Included among thesefactors is the dough formulation, the moisture content of the dough aswell as the farinaceous composition.

As the amount of wxsu₂ substitution is increased in a given doughformulation, the bakery product will become gummy resulting in a productwith a decreased volume. Also, bakery products containing wxsu₂ starchobtained from corn, when used in larger amounts result in productshaving a corn taste. This may be an advantage to some systems such ascorn or variety breads but a disadvantage in others such as whitebreads.

Other ingredients known to the skilled practitioner which are used toaid in production and/or to improve various quality factors of bakeryproducts may be employed in addition to the wxsu₂ starch herein. Suchingredients would include, for example, crumb softeners includingdistilled and hydrated monoglycerides, dough conditioners, doughstrengtheners, and emulsifiers. Knowledge of these various ingredientsand their interactions within a given dough formulation may determinethe benefits, if any, of their incorporation in a specific dough systemwith wxsu₂ starch.

In order to evaluate the breads described herein, two loaves wereprepared from each dough formulation. One loaf was evaluated shortlyafter baking while the other loaf was stored in a plastic bag for 3 to 4days before evaluation. A 35 mm thick slice was cut from the center ofeach loaf and evaluated employing a Stevens-LFRA Texture Analyzer run ata constant speed of 1mm/sec. The force (in grams) required to penetratethe bread a distance of 15 mm was then measured. A flat horizontal probe(#11) which measured 11/2 by 13/16 inches was used to evaluate the breadsamples shortly after baking. The aged bread samples which became firmerupon storage were usually evaluated with a second probe (#4), a 60°angle cone having a 11/2 inch diameter base. Due to the difference inshape between the two test probes, only comparisons between similarlytested samples may be made. Furthermore, due to variable bakingconditions, only samples prepared in the same manner and baked at thesame time were directly compared with one another.

The following examples will more fully illustrate the practice of thisinvention but they are not intended to limit its scope. In the examples,the wxsu₂ starch and flour employed are obtained from maize. All partsand percentages are given by weight and all temperatures are in degreesFahrenheit.

EXAMPLE 1

This example illustrates the effect of the addition of wxsu₂ starch orflour in a yeast leavened bread composition.

The following bread formulation and procedure were employed:

    ______________________________________                                        BREAD FORMULATION                                                             Ingredients          Grams                                                    ______________________________________                                        All Purpose Wheat Flour                                                                            380                                                      Water                230                                                      Sugar                18.85                                                    Shortening (plastic consistency)                                                                   10.0                                                     Salt                  9.35                                                    Active Dry Yeast      7                                                       ______________________________________                                    

The yeast was dissolved in warm (115° F.) water and allowed to stand forone minute. Thereafter the shortening and the blended remainingingredients were added to the yeast mixture. The mixture was mixed fortwo minutes on speed #1 of a Hobart Mixer then for an additional twominutes on speed #2. The dough was kneaded for four minutes then placedin a greased bowl, covered with a damp cloth and allowed to raise in acontrolled humidity cabinet (80% humidity and 85° F.) for 1.25 hours.The dough was thereafter punched down, divided in half and placed in twosmall aluminum pans. The dough was allowed to raise an additional houras before. The loaves were then baked for 20 minutes at 425° F. afterbuttering the tops. One loaf was allowed to cool before evaluating whilethe other was placed in a plastic bag after cooling for 2 hours.

Breads were prepared which contained 9.2% substitution levels based onthe total flour concentration of corn or waxy maize flour and comparedwith breads containing wxsu₂ starch or flour. The loaves were evaluatedas described above. Results may be found in Table I.

                  TABLE I                                                         ______________________________________                                                       Texture                                                                       2.5 Hours                                                                             2 Days                                                 Sam-                 Probe     Probe  Com-                                    ple  Flour Substitution                                                                            #11 (g)   #11 (g)                                                                              ments                                   ______________________________________                                        A    Control - no Additive                                                                         844       1000+  firm                                    B    9.2% corn flour 958       1000+  firm                                    C    9.2% waxy maize flour                                                                         870       1000+  very firm                               D    9.2% wxsu.sub.2 flour                                                                         678       1000+  soft                                    E    9.2% wxsu.sub.2 starch                                                                        308       600    softest                                 ______________________________________                                    

The results indicate that by employing either corn or waxy maize flourin the bread composition, the immediate texture and shelf stability ofthe bread was not improved. The use of wxsu₂ starch or flour, however,produced products which were initially softer as well as softer afterstorage than the control giving a preferred fresher appearance.

EXAMPLE 2

Breads were prepared as in Example 1 in order to compare formulationswhich contained wxsu₂ starch or flour with breads which containedpregelatinized wxsu₂ starch. The total flour concentration was 382 gramsinstead of 380 grams. The results may be found in Table II.

                  TABLE II                                                        ______________________________________                                                            Texture                                                                             2 Hours   3 Days                                                              Probe     Probe                                     Sample                                                                              Flour Substitution* #11 (g)   #4 (g)                                    ______________________________________                                        F     Control - no Additive                                                                             958       410                                       G     8.1% wxsu.sub.2 flour                                                                             792       298                                       H     8.1% wxsu.sub.2 starch                                                                            618       220                                       I     8.1% pregelatinized wxsu.sub.2 starch                                                             704       420                                       ______________________________________                                         *Samples G through I also contained 8 grams vital gluten.                

The results again showed that breads prepared with wxsu₂ starch andflour provided products with improved shelf-life. The use ofpregelatinized wxsu₂ starch was seen to provide no benefit in shelf-lifeover the control.

EXAMPLE 3

Breads were prepared in order to compare formulations employing waxymaize or wxsu₂ starch with a control bread formulation.

Breads were prepared as in Example 1 except the total flourconcentration was 382 grams instead of 380 grams. The control breadformulation was substituted with 8.1% wheat starch so that all thesamples contained a similar reduced gluten content. Waxy maize starchwith a reduced moisture content (7%) was employed because a similardough prepared with waxy maize starch having a normal moisture content(11-13%) was too sticky and unmanageable to shape into loaves. Theresults may be found in Table III.

                  TABLE III                                                       ______________________________________                                                         Texture                                                                             3 Hours   2 Days                                                              Probe     Probe                                        Sample                                                                              Flour Substitution                                                                             #11 (g)   #4 (g)*                                      ______________________________________                                        J     Control - 8.1% wheat starch                                                                    610       440                                          K     8.1% waxy maize starch                                                                         500       618                                          L     8.1% wxsu.sub.2 starch                                                                         385       358                                          ______________________________________                                         *Bread penetration distance was 21 mm instead of 15 mm.                  

The results show that wxsu₂ starch provided bread with a softer crumbinitially as well as after storage as compared with a control breadwhich had a similar reduced gluten content. Waxy maize starch providedbread with a firmer texture than the control after storage. The loaveswere also compared by a test panel after 2 days of storage. Sample Lcontaining wxsu₂ starch was rated overall the freshest in bothappearance as well as texture.

EXAMPLE 4

This example illustrates the effect of wxsu₂ starch or flour in a breadcomposition which also contains a crumb softener.

Breads were prepared as in Example 1 except the total flourconcentration was 382 grams instead of 380 grams. A total of 2.72 gramsof Panatex, hydrated monoglycerides which are useful as crumb softenersobtained from Paniplus, was added to the bread formulations. After fourdays of storage, the loaves were sensory evaluated by a panel of four.The staleness of the loaves was rated on a scale of 1 to 10 with 1 beingnot stale and 10 being extremely stale. Results may be found in TableIV.

                  TABLE IV                                                        ______________________________________                                                          Texture                                                                       3 Hours                                                                              4 Days                                               Sam-               Crumb    Probe  Probe                                      ple  Flour Substitution                                                                          Softener #11 (g)                                                                              #4 (g)                                                                              Rating                               ______________________________________                                        M    Control - no Additive                                                                       NO       680    390   --                                   N    Control - no Additive                                                                       YES      748    400   7.5                                  O    8.1% wxsu.sub.2 flour                                                                       YES      660    283   5.25                                 P    8.1% wxsu.sub.2 starch                                                                      YES      302    203   1.75                                 ______________________________________                                    

The results indicate that wxsu₂ starch or flour may be used inconjunction with crumb softeners to produce breads with improvedshelf-life.

EXAMPLE 5

This example illustrates the use of wxsu₂ flour in a chemically leavenedcorn muffin composition.

The following muffin formulations and procedure were employed:

    ______________________________________                                        CORN MUFFIN FORMULATION                                                                      Sample Q (Control)                                                                            Sample R                                       Ingredients    (g)             (g)                                            ______________________________________                                        All Purpose Wheat Flour                                                                      135             135                                            Corn Meal      163             149.96                                         wxsu.sub.2 Flour                                                                              0              13.04 (1)                                      Milk           227             227                                            Egg            43              43                                             Vegetable Oil  43              43                                             Sugar          28              28                                             Baking Powder    12.5          12.5                                           Salt             1.8           1.8                                            ______________________________________                                         (1) 4.36% substitution based on the total farinaceous concentration.     

The dry ingredients were blended then added to the liquid ingredientsand mixed on Speed #4 of a Hobart Mixer for one minute. The muffins werethen baked at 425° F. for 21 minutes.

After baking, the muffins were stored in plastic bags for two days andthen sensory evaluated by a test panel of six. The muffins were viewedunder yellow light in order to mask any slight difference in colorbetween the two muffin types. All panelists chose the muffins containingthe wxsu₂ flour as having a fresher appearance. These muffins were alsorated as having a fresher mouthfeel and texture over that of thecontrol.

EXAMPLE 6

This example illustrates the use of wxsu₂ starch in a chemicallyleavened muffin composition.

The following muffin formulation and procedure were employed:

    ______________________________________                                        MUFFIN FORMULATION                                                                           Sample S (Control)                                                                            Sample T                                       Ingredients    (g)             (g)                                            ______________________________________                                        All Purpose Wheat Flour                                                                      270             248.4                                          wxsu.sub.2 Starch                                                                             0              21.6 (1)                                       Milk           227             227                                            Sugar          45              45                                             Egg            43              43                                             Vegetable Oil  43              43                                             Baking Powder    9.7           9.7                                            Salt             3.6           3.6                                            ______________________________________                                         (1) 8% substitution based on the total flour concentration.              

The dry ingredients were blended then added to the liquid ingredientsand mixed for two minutes in a bowl with a spatula. The muffins werebaked at 400° F. for 21 minutes. After baking the muffins were storedfor 2 days then sensory evaluated by a panel of seven. Six of the sevenpeople found the muffins prepared with wxsu₂ starch to be fresher inappearance and texture.

We claim:
 1. In a farinaceous-based bakery product prepared from a doughcomprising a farinaceous material, an edible liquid, and a leavener, theimprovement which comprises the presence in the dough of an effectiveamount of a waxy starch from a plant of a wxsu₂ genotype andtranslocations, inversions, mutants, and variants thereof containing thewxsu₂ genotype, the amount being effective to improve shelf-life andsoftness retention of the baked dough.
 2. The dough of claim 1, whereinthe plant is corn.
 3. The dough of claim 2, wherein the waxy starch iswxsu₂ flour.
 4. The dough of claim 2, wherein the waxy starch is presentin an amount of about 3 to 15% based on the total farinaceous content ofthe dough.
 5. The dough of claim 4, wherein the waxy starch is presentin an amount of about 5 to 10%.
 6. The dough of claim 1, wherein theleavener is yeast.
 7. The dough of claim 1, wherein the leavener isbaking powder.
 8. The dough of claim 1, further comprising a crumbsoftener selected from the group consisting of distilled and hydratedmonoglycerides.
 9. The dough of claim 1, wherein the bakery product isselected from the group consisting of bread, buns, rolls, sweet doughs,muffins, quick breads, cakes and biscuits.
 10. A process for improvingthe shelf life of a leavened farinaceous-based bakery product, whichcomprises the step of replacing a portion of the farinaceous content ofthe bakery product dough with a waxy starch from a plant of a wxsu₂genotype and translocations, inversions, mutants, and variants thereofcontaining the wxsu₂ genotype, prior to baking the dough, thereplacement amount being sufficient to improve softness retention of thebakery product over an extended shelf life period.
 11. The process ofclaim 10 wherein the plant is corn.
 12. The process of claim 10 whereinthe waxy starch is wxsu₂ flour.
 13. The process of claim 10 wherein thewaxy starch is added in an amount of about 3 to 15% based on the totalfarinaceous content of the dough.
 14. The process of claim 10, whereinthe bakery product is selected from the group consisting of bread, buns,rolls, sweet doughs, muffins, quick breads, cakes and biscuits.